Internal combustion engine



Nav. 16, 1937. E. SCHIMANEK 2,099,278

- I INTERNAL COMBUSTION ENGINE Filed April 24, 1951 N 2 Sheebs-Sheet 1llllllll ll|l /JOM mwwm 46;

, Nov. 16. 1937. E. SCHIMANEK INTERNAL COMBUSTION ENGINE 2Sheets-SheetFiled April 24. 1931 Patented Nov. 16, I937 2,099,278INTERNAL-COMBUSTION ENGINE limil Schimanek, Budapest, HungaryApplication This invention relates to internal combustion engines whichwork with fuel injection, more particularly Diesel engines. The knowninternal combustion engines with fuel injection work either with directinjection of fuel into the cylinder or else with injection of fuel intoa preliminary chamber that precedes the working cylinder. In both casesthe fuel passes into the working cylinder in an atomized but stillliquid 0 form. This method of injecting fuel has disadvantages, whichrender the employment of such engines, particularly in the case of smallengines, impossible for high speeds of revolution. These disadvantagesconsist primarily in the fact that on thepne hand the atomization andregulation of the quantities of fuel to be ,introduced, particularly inthe case of small motors, are diflicult to efl'ectat ahigh speed ofrevolution, and

on the other hand in the fact that delayed ignitions occur. At the highpressures and the high fact that the fuel, before it burns, must beconverted from the form of a liquid to that of a vapour, the quantity ofheat requisite for this purpose being taken from the highly compressedair in the cylinder.

Now the object of this invention is to obviate these disadvantages in areliable manner, and the invention consists in the fact that the heatingof the liquid fuel under pressure on its way to the working cylinder iseflected. under such circumstances that the temperature .of preheatingapproaches as nearly as possible the vaporization temperature at theexisting pressure, but cannot exceed the latter temperature, so that themaximum preheating of the fuel, which is practicable without risk ofevaporation before injection is attained.

According to the invention this result is obtained by heating the fuelunder pressure by means of a heating device with automatic regulation independence upon the vaporization temperature corresponding to thispressure, or the 50 critical temperature, in such a way that thevaporization temperature is nearly reached but is -not exceeded, therebyattaining the maximum preheating of the fuel that is possible withouttherisk of vaporization before injection.

55 By this invention it is made possible to intro April 24, 1931, SerialNo. 532,397 In Austria April 25, 1930 '18 Claims. (01. 123-32) L ducethe fuel into the cylinder at a hi her pressure and at a highertemperature than corresponds to'the critical pressure and the criticaltemperature, which is mostly already reached at pressures lower thanthat-corresponding to the 5 injection pressure, this being effectedaccording to the invention by automatically regulating the heatingeffect in such a way that the formation of vapour cannot occur. Theinvention thereby also furnishes a means of successfully utilizing fuelsthat are dimcult to vaporizefor operating injection internal combustionengines, since the quantity of heat requisite for vaporization isalready supplied to the fuel before injection.

Such heating has primarily'the following advantages:--

(1) The volume of the liquid is increased by the heating, as a result ofwhich both the fuel pumps and'the holes inthe injection nozzles areenlarged, and the operating, both asregards the accurate functioning ofthe pump and as regards the choking of the nozzle holes, is improved; I

(2) Owing\to the fact that part of the fuel,

upon being injected into the cylinder, evaporates in consequence of'thefall of pressure occurrin on injection, the atomization is improved;

(3) Owing to'the formation of vapour, .and also owing to the betteratomization, the combustion is promoted and the duration of comfbustio'n shortened.

' Bysuch a process the result is also obtained that motors working withfuel injection (Diesel engines) can be operated at a higher speed ofrevolution than they could without preheating.

The above-mentioned advantages may become still more marked the morehighly the fuel to be injected is preheated under pressure. The limit ofthe liquid.

The formation of vapour can be reliably prefuel itself is employed asthe heating medium,

and the latter is at the same or a somewhat vaporization. of t e a ter yb r i b y p elower pressure than the fuel to be heated, the

vented by utilizing the vaporization of the liquid employed as theheating medium-in this case the same liquid as the fuelfor regulatingthe heater (electrical heater, lamp heater or the like), whereby afurther rise of temperature is. guarded against, or the vaporizationtemperature of the liquid heating medium, and at the same time thereforevthe .somewhat lower temperature of the liquid fuel, is permanentlysecured, provided the heater yields sumcient heat, that is to say,provided the heater is designed for the maximum load.

The said advantages may however also be utilized to the utmost limit,without the employment of a heat-transmitting medium, by effecting theregulating of the preheating by means of the vapour pressure or. thevapour density, or by the temperature of the fuel (liquid or vapour) tobe injected, the various magnitudes being utilized either singly or inany desired combination.

The utilization of the fuel vapour, the vapour density or thetemperature of the preheated fuel has the advantage that the desiredregulating can be reliably obtained even in the case of those fuels forwhich, as mostly occurs in practice, the thermal properties(relationship between vapour pressure and temperature'and so on) areunknown. I

If the vapour pressure is to be employed for regulation, theheatingwillaccording to the invention be carried out in such a way thatthe liquid, during the heating, is warmer at the surface or in theneighbourhood of the surface than at the deeper parts of the liquid. The

vapour that forms in the upper portion of the liquid is then utilizedfor regulating the heating, while from the lower and cooler portion ofthe liquid the pump sucks in the fuel to be injected.

Various forms of the process according to the inventionare illustratedby way of example in the accompanying drawings, in which Figurel showsfor purposes of comparison the known means for injecting fuel into theworking cylinder,

Figures 2 to 9 show diagrammatically in section'al elevation variousexamples of construction of the invention.

In the known fuel injection device illustrated\ in Figure 1, the liquidfuel is drawn in by suction by a fuel pump I through a suction valve 2,and is sprayed through a delivery valve 3, a pipe 4 and an atomizingaperture 5 into the cylinder 6, in which there moves a piston I.

The injection aperture 5 is controlled by a valve 9, which may beconstructed as the delivery valve of the pump. The injection valve mayhowever alternatively be non-mechanically controlled. Substantially thesame arrangement may be employed in :the case of preparatory chamberinjection. In the example of construction shown in Fig. 2 the pipe 4,which leads from the pump I into the cylinder-and in which the fuel issubjected to pressure, is so strongly preheated, electrically -,fo rexample, by means of a heating coil 8, that .iipon the pressure beingrelaxed by the opening of the injection valve 9, the evaporation of thequid fuel is brought about to an extent depend- Y nt upon the fall ofpressure and upon the preheating.

Preferably the arrangement is such that the delivery valve 3 of the pumpcloses the pipe l at g R the inlet point, and the injection aperture iscon-' q trolled. by a separate valve 9. This prevents d s- 'Thecompressor piston turbances occurring owing to any excessive preheatingof the liquid fuel in the fuel pump.

The heating apparatus 8 is adjustably constructed to enable thetemperature of preheating to beregulated in accordance with existingrequirements. Thus for example if electrical heating from a source ofenergy 8a is employed, the intensity of the heating may be so connectedwith the engine governor 8b, operatively connected with a variableresistor 80, that at higher governor positions, that is to say, at lowloads, the heating is less efiective than at lower gover-l norpositions, that is, at greater loads, since in the former case lessliquid fuel has to be preheated than in the latter case. It is alsoadvantageous to employ a pump I, of which the pressure can be regulatedmanually or automatically. Between the fuel pump I and the cylinder 6 isarranged a pump, compressor .or the like I2, I3, in which the liquidfuel preheated in the pipe 4 under pressure enters through the valve Ias a mixture of liquid andv vapour, while owing to the relaxation ofpressure when the valve I0 opens, a portion of the fuel is vaporized.This mixture of liquid and vapour is subjected by the compressor pistonI2 to a compression by which so much heat is supplied to the mixture ofliquid and vapour that the liquid still contained in the mix ture iswholly, or at least to some further extent, vaporized by the relaxationof pressure. Not only does this operation provide sufflcient heat forthe further vaporization of fuel not yet'vaporized but also insures,upon admission of the fuel to the cylinder, a better atomization of thedrops of liquid still present after the first atomization. I2 deliversthe fuel through the aperture of the valvethat acts as apressure-relieving aperture into the cylinder 6.

Figure 3 shows a constructional example in which the compression of theliquid already partially vaporized by the heating of the liquid and,

inder in a pre-compnessed condition. In this constructionalform, as thecompressor piston I2 descends, at first air flows through the pipe Itinto the cylinder, and then, when the piston uncovers the connectionleading to the valve I0, there flows in a mixture of liquid andvaporizedfuel, which is then compressed by the piston I2, and deliveredthrough the valve II, the pipe connection I I and the injection aperture5 into the cylinder '6. The valve I1 may even be omitted, its place as adelivery valve for the compressor being taken by the valve 9.Atomization upon relaxation of pressure in,the cylinder is thus promotedby the expansion of the air compressed with the fuel. This form of theprocess also renders possible a lower liquid pressure on the deliveryside of the fuel pump and a lower preheating of the liquid fuel as wellas the adoption of smaller injection velocities andpressuresffor theinjection of the fuel into the cylinder.

Figure 4 shows a constructional example with I pipe 4 to the injectionaperture, but through the medium of a liquid-which is provided in achamber surrounding the tube 4. This liquid may advantageously be thesame liquid asthe fuel employed. Should some other liquid be employed asa heating-medium, the boiling points of this liquid corresponding. morevarious pressures must be known.'.

The chamber I1 is closed at the top by a piston II or by some othermovable member, which is subject to the pressureof a spring |,8a, and bymeans of a lever l9, which can rotate about a point 20, aotuates a...regulating device 2|, by which the intensity of the heating means '8 isinflugnced. At'the bottom of the chamber "'1' is provided a shut-oifmember 22, by which any heating liquid that has escaped'by leakage orotherwise can be replaced. The piston I of the fuel pump is soconstructed that during the suc- -tion stroke it is moved by the cam Idof a cam disc lo and a lever lb, but during the compression stroke isunder the influence ofa spring la, the liquid pressure produced beingthereforeunambiguously determined by this spring. This point, there isevolved in the chamber II, at the liquid pressure determined by thepressure of the spring Illa, vapour, which moves the piston l8 anddiminishes the intensity of the heating until the temperature. of the.heating medium in the chamber I1 is kept steadily at the level of thevaporization temperature. This temperature is therefore steadilymaintained in the chamber 11' independently of whether more fuel or lessfuel isiiowing through the tube 4 to the cylinder. This fuel istherefore always heated right up to that temperature which correspondsto the vaporization temperature of the heating. liquid, which may beliquid fuel, at the pressure prevailing in the chamber Figure 5 shows aconstructional example in which a superheatingof the fuel oravaporization thereof is prevented by the fact that the heat transmittedto the liquid heating medium by excess heating generates vapour, whichis condensed on a cooled surface 23a. The heating device 8 is h rerepresented as an electrical device, and by eans of the heating liquidin the chamber l'l'j heat is transmitted to the liquid fuelflowing'through the pipe 4. The pressure in the chamber I1 is adjustedby means of the piston l8 and the spring l8a, as explained in connectionwith the preceding example, and is harmonized with the spring la. Theheat transmitted to the liquid heating medium by overheating is hereremoved owing to the a fact that the vapour produced by overheatingpasses through the pipe/Ila into a cooling vessel 23, where the vapouris condensed. There will always heated to one and the same temperature,quite independently of the load.

Figure 6 shows a constructional example in which, when employing thefuel itself as a heating liquid, ,the pressure in the chamber IT isconnected with that in the tube 4 throughthe medium of the piston 18 insuch a way that upon one side of the piston l8 there acts the pressurein the chamber 4, and on the other side of the piston there act'thepressure in the chamber l1 and the pressure of the spring 18a, wherebythe pressure in the chamber H is kept lower than that in the tube 4.

Figure "I shows the solution, in which in the chamber l1 and in the'chamber 4 the same pressure is established by connecting these twochambers with'one another, in which case the pump delivers into achamber, from which the pipes 4, I11) and 23a branch off. The vapourgenerated in the chamber I1 is here condensed in the tube I11: and 23.In this case the pump I may be moved positively even during the deliverystroke instead of by a spring.

Figure 8 shows a constructional example of a step-by-step preheating ofthe fuel, which is regulated by the pressure of the vapour.

The pump. draws fuel by suction out of the tank 3| and delivers it intothe first heating vessel 32. This vessel is heated by an electricalheating device 33 on the cylindrical surface. The regulating of theheater is effected by means of a piston 34, which co-operates with thevessel 32, and which, by meansof a lever 36 under the action of a spring35, actuates electrical regulating means 31.

To the vessel 32-is connected at the bottom'the suction pipe of a pump38; which draws in fuel from the bottom of the vessel 32 and delivers itinto the heating vessel 39, which is heated by an electrical heater 40,this heater being regulated by a piston 4| 'through the medium of alever 43' acted upon by a spring 42, and an electrical regulating device44. q To the bottom of the vessel 39 is connected the suction pipe of apump 45, which'draws the fuel out of the lower portion of the vessel 38and delivers it directly or through a mechanically con trolled .val e 46intciv the motor cylinder 41. In

the former case, that is with direct delivery, the valve 46 is omitted,and the pump delivers the fuel through an open nozzle 48 into thecylinder, in which case however the delivery valve of the pump ispositively controlled.

'I'he method of operation of the heat-regulating means is as follows:

As soon as the temperature in the heating ves- .sel 32, owing to theaction of the heater, has ex-' ceeded' the temperature corresponding tothe vapour pressure, which is uniformly determined by spring pressureand by the diameter of the perature corresponding to the pressureestablished in the vessel by the force of the spring is maintained.

The form of the tank, which is a high vertical cylinder, and thearrangement of the heater in the cylindrical surface, have the resultthat the liquid in the neighbourhood of the surface will be a fewdegrees warmer than in the lower portion. The formation of vapour istherefore limited to .the uppenportion of the liquid, while from thelower portion, or infact from the lowest point,

liquid is drawn out by the suction of the pump 38. The pressure in thetank 32 and in the tank 39 can be regulated at will owing to the designof the springs 35 and 42 respectively.

The pump 45 sucks liquid from the vessel 39 under a lower pressure thanthat at which the injection is to occur.

It will be obvious that either direct injection or preparatory chamberinjection may be employed.

The speed of revolution of the pump 45 is determined by the speed ofrevolution of the motor 41 and the number of strokes per cycle, whilethe pumps 38 and 30 may be operated at any convenient speed ofrevolution. The pump is thus operated in timed relation with the engine,and in predetermined relation with valve 45 so that such pressurevariations as occur in chamber 39, fall within a comparatively limitedrange. The resultant pressure rises in response to the superaddedpressure of generated vapor and causes actuation of the control device44.

The heating of the fuel may alternatively be carried out in a singlestage, by the aid of a single heating vessel." In this case the pump 30and the heating tank 32, together with the equipment thereof, areomitted and the 'pump 38 sucks directly out of the fuel tank 3|.

If the regulating of the heater or of the fuel preheating is noteffected by the vapour pressure but by the vapour density, for thepurpose of obtaining a preheating approximating to the criticaltemperature of the fuel, the regulating of the heater may be obtainedwith a suitable boiler water level protection apparatus, such forexample as that shown in Fig.9. The-heating right to the critical pointhas the advantage, in addition to those mentioned above, that at, thecritical temperature "the liquid volume is a maximum, and at thistemperature the liquid and the vapor have the same volume, that is tosay, the accurate measuring of the quantity of fuel sucked in by the.pump cannot be disadvantageously affected by the pump sucking in amixture of vapor and liquid. The regulating of the heating when thecritical point is to be reached may be carried out on the basis of theprinciple that at this temperature the vapor and the liquid are of thesame volume and of the same density. Any automatic boiler water levelregulating device can therefore be used as described above, the actionof these devices in general being based upon the fact that vapor andliquid are of different specific gravities, or

influence the thermoconductivity or the electrical resistancedifferently.

In Figure 9 is shown as a constructional example a device which acts byelectrical means.

In the heating vessel 50, in which the liquid level is secured by meansof a discharge pipe 5|, an electrical conductor or an electricalresistance 52 is lodged in the liquid space' and a second electricalresistance 53 in the vapour space of the vessel. Both resistances aremade of a material of which the electrical resistance changes accordingto the nature or density of the medium in delivered by a source ofcurrent 59 flows through the heating wire 50 of the vessel 50. As soonas the condition in the heating vessel has reached the critical point ofthe fuel, the resistances 52 and 53 become equal inmagnitude. The bridge55 then carries no current, and the relay 51 allows the contact lever 6|to fall, whereby the contact 58, and therefore the heating circuit areinterrupted.

What I claim is:--

1. A method of operating internal combustion engines with liquid fuelinjection, particularly Diesel engines, comprising supplying liquid fuelto the engine 'under pressure, heating the liquid fuel while on its wayto the engine cylinder under pressure through an interposed liquidbetween the source of; heat and the liquid fuelto be heated, the saidliquid forming the means of transmitting heat from the source to thefuel, regulating the heating of the fuel to be injected to maintain thetemperature thereof interme- 'diate its vaporizationtemperature underpres-- sure before injection and its vaporization temperature at thelower pressure within the cylinder to thereby maintain the fuel in theliquid state prior to its introduction into the cylinder and to provide"sufficient heat in the fuel so that it is vaporized as a result of theheat contained therein when introduced into the cylinder at said lowerpressure, and then injecting the fuel into the engine cylinder. 7

2. A .method of operating internal combustion engines as claimed inclaim 1, further comprising interposing some of the fuel-liquid, as ameans for transmitting heat, between the source of heat and the liquidfuel to be heated. I

3. A method of operating internal combustion Y 4. A method of operatinginternal combustion engines as claimed in claim 1, further comprisingutilizing the vapour of the heat-transmitting liquid as a means forautomatically regulating the heating of the liquid fuel, the said vapourexerting a compensating'action by its condensation.

5. A method of operating internal combustion engines with liquid fuelinjection, particularly Diesel engines, comprising supplying liquidfuelto the engine under pressure, heating the liquid fuel while on its wayto the engine cylinder under pressure, the heating \of the liquid fuelbeing eflected in such a manner that the fuel becomes warmer at and nearthe surface than lower down, and utilizing the vaporization of theliquid at the surface for regulating the heating of the fuel to beinjected to maintain the temperature of said fuel intermediate itsvaporization temperature under pressure before injection and itsvaporization temperature at the lower pressure withinthe cylinder tothereby maintain the fuel in the liquid state prior to its introductioninto the cylinder and'to provide sufllcient heat in the fuel so thatvaporization results because of the.

heat contained therein when introduced into the cylinder at said lowerpressure, and then introducing the fuel into the engine cylinder.

- 6. A method of operating internal combustion engines with liquid fuelinjection, particularly Diesel engines, comprising supplying liquid fuelto the engine under pressure, heating the liquid fuel while on its wayto the cylinder under pressure to a regulated temperature intermediateits vaporization temperature under pressure and its vaporizationtemperature at the lower pressure within the cylinder, the heating ofthe liquid fuel liquid fuel being -withdrawn from the lower part of thesaid vessel by-a fuel pump, for injection into the engine cylinder,at atemperature that is a few degrees below the saturated vapour teming inthe heating vessel. I

perature corresponding to the pressure prevail 7. A method of operatinginternal combustion engines with liquid fuel injection, particularlyDiesel engines, comprising supplying liquid fuel to the engine underpressure, heating the liquid fuelwhile on its way to the cylinder underpressure to a regulated temperature intermediate its vaporizationtemperature under pressure and its vaporization temperature at the-lowerpressure within the cylinder, the heating of the liquid fuel beingeffectedin such a manner that the fuel becomes warmer at and near thesurface than lower down, the vaporization of.the liquid at the surfacebeing utilized for regulating the heating, and .the vapour pressureallowed ,being determined by means .of an adjustable-spring.

8. A method of operating internal combustion engines with liquid fuelinjection, particularly Diesel engines, comprising supplying liquid fuelto the engine under pressure, heating the liquidfuel while on its way tothe cylinder under pressure to a regulated temperature intermediate itsvaporization temperature under pressure and its vaporization temperatureat the lower pressure within the cylinder, the preheating of the liquidfuel being effected in successive stages, and in.

each stage to a temperature a few degrees below the saturated vapourtemperature corresponding to the pressure prevailing in the said stage,and

the pressure in the last stage being lower than the injection pressure.1

. 9. A method of operating internal combustion engines with' liquid fuelinjection, particularly Diesel engines, comprising supplying liquid fueltothe engine under pressure, heating the liquid 7 fuel While on its wayto'the cylinder under presi sure, regulating the heating of the fuel upto the the fuel into the engine cylinder.

10. A method of operating internal combustion engines with liquid fuelinjection particularly Diesel engines, comprising supplying liquid fuelto the engine under pressure, heating the liquid fuel 1while-on its wayto the cylinder under pressure,

regulating the heating of the fuelby means of A the difference inphysical properties between the vapour and the liquid to maintain thetemperature thereof intermediate its vaporization temperature underpressure before injection and its vaporization temperature at the lowerpressure within the cylinder tothereby maintain the fuel in the liquidstate prior to its introduction into the cylinder and to providesuflicient heat in the fuel so that jvaporizationresults because of theheat contained therein when introduced into the cylinder at said-lowerpressure,- and then injecting the fuel into the engine cylinder.

- 11. A method of operating internal combustion engines with liquid fuelinjection, particularly Diesel engines, comprising supplying liquid fuelto the engine under pressure, heating the liquid fuel while on itsway't'o the cylinder under pressure, regulating theheating of the fuelby utiliz ing the difference-in density between the vapour and liquidfuel to-. maintain the temperature thereof intermediate its vaporizationtempera-- ture under pressure before injection and its vaporizationtemperature at the lower pressure within the cylinder to therebymaintain the fuel in'the liquid state prior to its introduction into thecylinder and to provide, 'sufficient heat in the fuel so thatvaporization res ts because of the heat contained therein whenintroduced into the cylinder at said lower pressure, and-:then injectingthe fuel-into the engine cylinder.

12. In an internal combustion engine iof the character described havinga source of liquid fuel,

the combination of regulable means for heating'\;, the fuel prior to itsinjection into the engine to .a ,point such that the fuel will bevaporized through the reduction of'pressure and the heat contained inthe liquid itself upon injection into the engine, means cooperating withsaid heating means for preventing the application of such, quantitiesofheat tothe fuel that it is vaporized prior.to its injection, and meansfor injecting the heated non-vaporized fuel into the engine.

the engine cylinder, a heating liquid chamber surrounding the fuelchamber and communicating directly therewith, and cooling means forliquid chamber.

14. In an internal combustion engine of the character described having asource of liquid fuel, the combination of regulable means for heatingthe fuel prior to-its injection into the engine to a point suchs/thatthe fuel will be vaporized through thereduction of the pressure and theheat contained in the liquid itself upon -injection into theengine,.means cooperating with said heatin means and actuated inaccordance with the diffe ence in physical properties between'the vaporand liquid for preventing the application. of such quantities of heat-tothe fuel that it is vaporized prior to its injection, and means forinjecting the heated non: vaporized fuel intothe engine. I

15. In an internal combustion engine of the character described having asource of liquid fuel, a combination of regulable means for heating thefuel 'prior to its. injection into the engine to a: point such that thefuel will be vaporized through the reduction of the pressure and theheat contained in the liquid itself upon injection into,the engine,means responsive respectively to the densities of the liquid fuel andits vapour, and means cooperating t lith"saidv heating means andcontrolled by said density responsive means for preventing theapplication of suchquantities of heat to the fuel that it is vaporizedpriorto its injection, and means for injecting the heated non-vaporizedfuel intothe' engine.

16. In any internal combustion engine of the character described havinga source of" liquid liquid fuel, comprising a fuel chamber leading tocondensing the vapour generated in the: heating i heating means forpreventing the application of such quantities of heat to the fuel thatit is vaporized prior'to its injection, said last mentioned meansincluding means responsive to the vapour pressure of the fuel, and meansfor regulating said heating means to reduce the quantity of heatsupplied to the fuel upon increase in vapour pressure thereof, and meansfor injecting the heated non-vaporized fuel into the engine.

1'1. In an internal combustion engine having a supply of liquid fuel,the combination of means for subjecting the fuel to pressure, means forpreheating the liquid fuel to a temperature closely approaching but notexceeding its vaporization temperature corresponding to its pressure,means providing for a preliminary relaxation of pressure withvaporization of a portion of the fuel, compressor means for compressingthe mixture of vapor and liquid with the production of a quantity ofheat, and means for injecting the fuel into the engine cylinder withfurther vaporization of theliquid portion thereof.

18. In an internal combustion engine having a supply of liquid fuel, thecombination of means for subjecting the fuel to pressure, regulablemeans; for preheating the liquid fuel to a temperature closelyapproaching but not exceeding its vaporization temperature correspondingto its a pressure, means providlngfor a preliminary re-

